Date: Sat, 17 Jun 2000 08:06:22 -0700 From: Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca> To: freebsd-stable@freebsd.org Subject: ATA DMA Problem Message-ID: <200006171506.e5HF6sg00904@cwsys.cwsent.com>
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I've discovered an interesting problem as follows:
Jun 17 05:16:59 cwsys /kernel: ad2: HARD READ ERROR blk#
4999424ata1-master: WAR
NING: WAIT_READY active=ATA_ACTIVE_ATA
Jun 17 05:16:59 cwsys /kernel: ad2: DMA problem fallback to PIO mode
Jun 17 05:16:59 cwsys last message repeated 15 times
The IDE devices attached to the system are:
Jun 17 07:06:31 cwsys /kernel: ata0: at 0x1f0 irq 14 on atapci0
Jun 17 07:06:31 cwsys /kernel: ata1: at 0x170 irq 15 on atapci0
Jun 17 07:06:32 cwsys /kernel: ad0: 2014MB <WDC AC22100H> [4092/16/63]
at ata0-m
aster using WDMA2
Jun 17 07:06:32 cwsys /kernel: ad2: 2441MB <WDC AC22500L> [4960/16/63]
at ata1-m
aster using WDMA2
At first glance it looks like a bad block on disk. However, the errors
only occur when running:
dd if=/dev/ad0 of=/dev/null bs=1024k
After running the Western Digital wddiag scan three times, without
indication of error, and running:
dd if=/dev/ad0 of=/dev/null (notice no bs=1024k)
... also without error.
... and running the dd with bs=1024k a number of times subsequent to
this, the above error can be repeated 100% of the time when dd is run
with bs=1024k specified. (Just a hunch but bs=64k would probably not
cause the error -- will have to test that theory out).
Otherwise the system and disk have been running nicely, so this is not
a major issue. It is an interesting problem of which I don't have too
much data collected and therefore feel awkward submitting a PR
regarding this.
I suspect one of the following:
1. Possible heat problem, bs=1024k probably drives the disk harder than
the default bs=512. Interestingly, 3.4 didn't experience this
problem.
Maybe 4.0's new ATA driver is more efficient, driving the disk
harder
and causing the disk's controller board to run a little hotter than
it
did under 3.4. (most)
2. Possible disk/controller/DMA timing issue, e.g. hardware problem
excluding HDA failure.
3. Possible FreeBSD ATA/DMA driver bug. (least)
I'm running 4.0S as of May 27.
Any comments would be welcome.
Regards, Phone: (250)387-8437
Cy Schubert Fax: (250)387-5766
Team Leader, Sun/DEC Team Internet: Cy.Schubert@osg.gov.bc.ca
Open Systems Group, ITSD, ISTA
Province of BC
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